I am doing a build with a linear (mohgasm) driver at 1.62A and my battery options are leaning toward one of those 3x10440 things. If I do that, do I just solder one connection over and use two batteries?

I'd rather do a 2x16340 or 2x18350 - where do you guys get the plastic inserts for these batteries to make them fit snugly in a host!

10440 from AW are 340mAh i guess so at 1.62A you're asking a 5C+ discharge..
You'll drain it in a couple of runs.. 18350's are well suited,
to fit the batteries, you make them yourself or buy them.. I use a transparency paper, cut it to the desired size (carefully) and scotch-tape the ends, then you can order some of them like this one or similar as required, n replace them with your ghetto ones.